The cognitive functioning of a human brain depends on a delicate orchestration of many factors, especially during the critical stages of embryo development-and it is much more likely that this self-organizing structure, to be enhanced, needs to be carefully balanced, tuned, and cultivated rather than simply flooded with some extraneous potion.
Nick BostromFar from being the smartest possible biological species, we are probably better thought of as the stupidest possible biological species capable of starting a technological civilization - a niche we filled because we got there first, not because we are in any sense optimally adapted to it.
Nick Bostrom